At least on adwords, you get a "quality score" for ads, which is essentially a clickthrough rate, which lowers your cost per impression. In this case, I assume

At least on adwords, you get a "quality score" for ads, which is essentially a clickthrough rate, which lowers your cost per impression. In this case, I assume those ads get a high clickthrough rate due to being terribly misleading, which leads the algorithm to believe these ads are the most appropriate for this ad slot (they are if the only metric you care about is money going into Google's pockets).